1. Field of the Invention
The present invention relates, in general, to washing machines and, more particularly, to a washing machine having a wobbling unit which wobbles a washing plate installed in a spin-drying tub, thus washing laundry.
2. Description of the Related Art
As is well known to those skilled in the art, a vertical shaft type washing machine is designed such that a cylindrical spin-drying tub and a cylindrical washing tub are vertically set in a housing, and a pulsator is installed in the cylindrical spin-drying tub and rotated in alternating directions, thus washing laundry inside the cylindrical spin-drying tub by forced water currents generated by the pulsator. FIG. 1 illustrates an interior of a conventional vertical shaft type washing machine.
As illustrated in FIG. 1, the conventional vertical shaft type washing machine 300 with a pulsator 4 includes a housing 1 which defines an external appearance of the washing machine. A washing tub 2 having a cylindrical shape is vertically set in the housing 1 and contains wash water therein. A cylindrical spin-drying tub 3 is rotatably and concentrically set in the washing tub 2. The cylindrical spin-drying tub 3 is perforated on a sidewall thereof to have a large number of spin-drying perforations 3c. The pulsator 4 is interiorly installed on a bottom of the cylindrical spin-drying tub 3, and generates wash water currents inside the cylindrical spin-drying tub 3. The washing machine has a drive motor 5 and a power transmission unit 6. The drive motor 5 and the power transmission unit 6 are installed in a space between a bottom of the washing tub 2 and a bottom of the housing 1 to selectively rotate the pulsator 4 and the cylindrical spin-drying tub 3.
The housing 1 is opened at a top thereof to allow a user to put laundry into or take out laundry from the cylindrical spin-drying tub 3. A door 7 is hinged to the top of the housing 1 to open or to close the cylindrical spin-drying tub 3. Further, a drain hose 8 extends from the bottom of the washing tub 2 to an outside of the housing 1 so as to discharge the wash water from the washing tub 2 to the outside of the housing 1 when a washing process is completed.
A spin-drying shaft support unit 9 is mounted to a bottom plate 3a of the cylindrical spin-drying tub 3 to connect a spin-drying shaft 6a of the power transmission unit 6 to the cylindrical spin-drying tub 3, so that the cylindrical spin-drying tub 3 is rotated by a rotation of the spin-drying shaft 6a at a spin-drying operation. A washing shaft 6b of the power transmission unit 6 passing through the spin-drying shaft 6a is connected to the pulsator 4 interiorly installed on the bottom of the cylindrical spin-drying tub 3, so that the pulsator 4 is rotated by a rotation of the washing shaft 6b at a washing operation.
In the conventional vertical shaft type washing machine, when the conventional vertical shaft type washing machine 300 operates after putting the laundry into the cylindrical spin-drying tub 3, water is supplied to the washing tub 2. Further, the washing shaft 6b of the power transmission unit 6 rotates in alternating directions by the drive motor 5, so the pulsator 4 is rotates in corresponding directions. By the rotation of the pulsator 4, the water currents are generated in the alternating directions, so the laundry is washed while being moved along with the water currents.
When the washing operation is complete after a predetermined period of time, the wash water is discharged to the outside through the drain hose 8. Further, a rinsing operation is performed to remove a detergent from the laundry. Thereafter, the spin-drying shaft 6a is rotated by the drive motor 5 so that the cylindrical spin-drying tub 3 rotates in a single direction at a high speed, thus spin-drying the laundry. Therefore, all operations to wash the laundry are completed.
However, the conventional vertical shaft type washing machine 300 is designed such that the laundry is washed by the water currents generated when the pulsator rotates in the alternating directions, so the laundry is also rotated in alternating directions, and thereby the laundry is twisted and is tangled together. Thus, the conventional vertical shaft type washing machine has a problem that the laundry is easily worn out and is damaged, and a user must disentangle the laundry when the washing process is complete, thus being inconvenient to use and causing a waste of time.
Further, the conventional vertical shaft type washing machine using the pulsator has another problem that the pulsator is rotated in the alternating directions at short intervals during the washing operation, so that a power consumption is increased and a life-span of the drive motor is shortened due to a repeated reversible rotation of the drive motor.
Since the conventional vertical shaft type washing machine 300 using the pulsator is designed to wash the laundry by forcibly moving the laundry clockwise and counterclockwise by the water currents, a large amount of the wash water must be supplied to the washing tub, so water consumption is increased and detergent consumption is increased due to the high water consumption. Thus, the conventional vertical shaft type washing machine has a further problem that it causes a waste of the water and causes environmental contamination due to a high detergent consumption. Since a saving of water and protection of environment have been increasingly stressed in recent years, the above-mentioned problems must be solved.